I remember buying this comic for the cool cover. The Signalman story was OK, but the back up story was great! Green Arrow and the Elongated Man go to a ball game and run into … the Calculator. Green Arrow turns himself into a human arrow and Elongated Man into the bow. Crazy!
(The Calculater was a cheesy villain who would let himself get caught by different superheroes, and then compute how to defeat them after his next escape. (The storyline culminates with his victory over the entire “Justice League” in Detective Comics #468. Batman, of course, figures out how to defeat him for good.)